Vacuum check valve



FIG. 1 is a front elevational view of my design;

FIG. 2 is a right elevational view of my design;

FIG. 3 is a rear elevational view of my design;

FIG. 4 is a left elevational view of my design;

FIG. 5 is a bottom view of my design; and,

FIG. 6 is a top view of my design.

The ornamental design for a vacuum check valve, as shown and described.